1. Upload a chapter with a delay
2. Delete that chapter
3. Wait for the delay to end and check that manga's RSS page
This bug can be observed here: https://mangadex.org/rss/nZWKABXGxm7sC5pQtSezMca62EPkT8Nr/manga_id/12714
Chapter 231 showed up in my feed yesterday despite the fact that it had...